critical pressure

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critical pressure

[′krid·ə·kəl ′presh·ər]
(fluid mechanics)
For a nozzle whose cross section at each point is such that a fluid in isentropic flow just fills it, the pressure at the section of minimum area of the nozzle; if the nozzle is cut off at this point with no diverging section, decrease in the discharge pressure below the critical pressure (at constant admission pressure) does not result in increased flow.
(thermodynamics)
The pressure of the liquid-vapor critical point.

Critical Pressure

 

the pressure of a substance or mixture of substances in the critical state. At pressures less than the critical pressure, the system may dissociate into two equilibrium phases, a liquid and a gas. At the critical pressure the physical distinction between the liquid and gas is lost, and the substance undergoes transition to a single-phase state. Thus, the critical pressure may also be defined as the limiting (highest) saturated vapor pressure under conditions of existence of the liquid and vapor phases.

The critical pressure is a physicochemical constant of the substance. (For values of the critical pressure pc of a number of substances, see Table 1 in CRITICAL POINT.) The critical state of mixtures differs in the dependence of the critical pressure on the composition and thus exists not at a single critical point but on a curve on which all points are characterized by critical values of pressure, temperature, and concentration.

critical pressure

The highest pressure of the fuel-air mixture inside the cylinder of a reciprocating engine that allows a mixture to burn evenly, rather than detonate or explode.
References in periodicals archive ?
Repeating the experiment at different levels of pressure determines at a given temperature the characteristic critical pressure beyond which the crack propagates over more than 90% of the pipe length.
Once the gas company has determined its MOP, the RCP requirement is the critical pressure of the pipe must be (at least) 1.
DNV GL strongly advises the operators of PE gas pipe distribution systems to determine whether pipe materials used within their systems have been My tested to determine the RCP critical pressure level.
He reported an increase in the critical pressure from 3.
Harry (15) concluded that shear lips provide the bulk of the pipe resistance to RCP, as seen from the significant reduction in RCP critical pressure [P.
Comparison of the minimum required and measured FS critical pressures in Table 4 shows that the FS Pc results are greater; thus, the unimodal MDPE pipe tested in this study have sufficient RCP resistance for use in gas distribution systems.
Unimodal MDPE pipe in diameters up to 219 mm exhibits RCP critical pressures that exceed the Minimum Required Critical Pressure for use in gas distribution systems, thereby delivering very adequate RCP performance.
ICIS has recognized a growing interest in sustainable chemistry among its members, even as critical pressures like materials pricing, staff reductions and cash flow intensify," said John Baker, global editor for the ICIS custom publishing unit.
Ashcroft gauges and pressure transducers were utilized to monitor all critical pressures at the station.
However, the critical pressures are controlled by the true stresses at the walls, and these are only affected by the geometry of the entrance region and the die itself.
We call this shear rate and the corresponding pressure drop the critical shear rate and the critical pressure drop.